Abstract: An optical apparatus comprising a gain medium exhibiting polarisation dependent absorption along two axes, the gain medium having a weakly absorbing axis and a strongly absorbing axis, an optical pump source arranged to direct pump light towards a first face of the gain medium such that the pump light entering the gain medium has a component of its polarisation parallel to the weakly absorbing axis, a polarisation modifying apparatus and one or more reflectors which are together arranged to modify the polarisation of pump light which exits the gain medium through a second face of the gain medium, and to direct the pump light with modified polarisation back towards said second face of the gain medium.

Abstract: Method and apparatus are disclosed that enable lasers to be stabilized in absolute frequency to high precision. The principle of operation is to: 1) lock the laser frequency to an etalon transmission resonance, 2) phase modulate the laser beam at a frequency corresponding to the free spectral range of the etalon and lock the phase modulated sidebands to the etalon resonances, and 3) lock the etalon free spectral range frequency to a stable reference frequency derived from, e.g., a stable crystal oscillator. The result is that the laser frequency is locked to an integer multiple of the reference frequency. The invention has applicability to numerous situations where a stable frequency must be provided at a specific value, and has further applicability to stabilizing multiple lasers in different locations to the same value.

Abstract: A laser source (10) for emitting a set of sequential, different wavelength output beams (12) includes a gain medium (16), a feedback assembly (26) and a control system (30). The gain medium (16) includes a first facet (16A), and the gain medium (16) generates a beam (12A) that exits the first facet (16A). The feedback assembly (26) includes a feedback device (40) and a device mover (42). The feedback device (40) is positioned in the path of the beam (12A) that exits the first facet (16A) and the feedback device (40) redirects at least a portion of the beam (12A) back to the gain medium (16). The device mover (42) continuously adjusts an angle of incidence (?) of the beam (12A) on the feedback device (40). The control system (30) selectively directs pulses of power to the gain medium (16) as the device mover (42) is continuously adjusting the angle of incidence (?) of the beam (12A).

Abstract: The disclosure relates to an illuminating apparatus for illuminating a sample on a work stage, optionally with a relatively narrow illuminating line of relatively controlled energy, as well as methods for controlling energy of a laser source when illuminating a sample on a work stage with a relatively narrow illuminating line.

Abstract: The invention discloses an optical transmission module with digital adjustment and method thereof. The module includes a laser (21), a laser driver (22), an automatic power adjustment circuit (23), an automatic temperature adjustment circuit (24), a digital adjustment circuit (25) and a memory (26). The digital adjustment circuit, consisted of a digital-to-analog converter or a digital adjustment potentiometer, receives a digital adjustment signal and outputs, respectively, a extinction ratio adjustment signal and a cross point adjustment signal to the laser driver, an optical power adjustment signal to the automatic power adjustment circuit and an optical wavelength adjustment signal to the automatic temperature adjustment circuit. The memory stores data, using for on-line adjustment of the optical transmission module, at least including parameters of said optical transmission module and said laser emitting optical power parameters, to be reported upward.

Abstract: The luminance of a laser diode is a function of laser diode drive current. The luminance is also a function of other factors, such as age and temperature. A laser projection device includes laser diodes to generate light in response to a commanded luminance, and also includes photodiodes to provide a measured luminance. The commanded luminance and measured luminance are compared, and drive currents for the laser diodes are adjusted to compensate for changes in laser diode characteristics.

Abstract: A Light receiver generates a monitoring voltage according to an optical output of an LD element. The control circuit obtains a set value according to the ambient temperature around the LD element, and controls the optical output of the LD element on the basis of the comparing the result between the set value and the monitoring voltage. An adjustment section corrects the monitoring voltage on the basis of the set value and outputs the corrected monitoring voltage.

Abstract: In a laser power control apparatus for controlling a laser power of a combination drive, first laser light Lc applied onto a first optical disk and second laser light Ld applied onto a second optical disk is collected by one photodetector 8.

Abstract: A semiconductor laser drive system and a semiconductor laser driving method where both internal noise and optical feedback noise can be simultaneously reduced are provided at low cost and low power consumption.

Abstract: A method of protecting a laser against damage caused by undesired incident light in a resonator includes measuring a parameter, which is a measure for the optical power of the incident light. In more concrete terms, the optical power occurring at a resonator mirror is measured. In response to a result of the measurement, a pumping power for the laser is reduced to reduce the optical power in the resonator to a value that is uncritical for the laser.

Abstract: The invention describes classes of robust fiber laser systems usable as pulse sources for Nd: or Yb: based regenerative amplifiers intended for industrial settings. The invention modifies adapts and incorporates several recent advances in FCPA systems to use as the input source for this new class of regenerative amplifier.

Abstract: An efficient and low-noise solid-state laser is optically pumped by one or more laser diode(s) driven by RF modulated current. The solid-state laser operation is stabilized by the pump source stable in both spectrum and intensity, in conjunction with automatic power control wherein the feedback loop accurately reflects the true drift in the output power. Moreover, the pump efficiency is optimized and the optical noise is minimized by adjusting the diode operation temperature such that the pump wavelength coincides with the absorption peak of the gain medium. By internally or externally modulating the amplitude of the drive current, the pump diode(s) operate in pulsed mode with controllable shape, width, repetition rate, and pulse-to-pulse intervals, which enables essentially constant optical energy produced from each pulse of the solid-state laser in high repetition rates with variable pulse-to-pulse intervals.

Abstract: A laser projection device suitable for displaying full color images is disclosed. The LPD includes a variety of techniques for modulating laser beams produced by one or more lasers with image data to controllably produce the image using a modified raster scan.

Abstract: A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Abstract: According to one embodiment of the present invention, a programmable light source comprises one or more semiconductor lasers, a wavelength conversion device, and a laser controller. The controller is programmed to operate the semiconductor laser using a modulated feedback control signal. The wavelength control signal is adjusted based on the results of a comparison of a detected intensity signal with a feedback signal to align the lasing wavelength with the conversion efficiency peak of the wavelength conversion device. Laser controllers and projections systems operating according to the control concepts of the present invention are also provided.

Abstract: The bias current of a current injection-type light-emitting element is set very close to the threshold current, and to guarantee a stable optical output and high-speed initiation of the light-emitting operation. In the bias current supply circuit 12, particularly in closed-loop circuit 20, feedback operation of bias APC with variable bias current Ib is performed so that monitor voltage VM1 comes to equal reference voltage VA1. With this feedback operation, the steady state of VM1=VA1 is reached, and drive current Ib (Iba+Ibb) sent to laser diode 10 converges to a constant value. After a prescribed time, S/H circuit 34 is switched to hold mode. As a result, drive current Ib (Iba+Ibb) is temporarily held to a constant value corresponding to the prescribed optical output.

Abstract: Systems, devices and methods of generating both a precision electrical timing signal as well as a precision optical timing signal. A novel, modified opto-electronic loop oscillator is used to drive a harmonic mode-locked laser. A novel opto-electronic loop has a larger “Q” factor by increasing the electrical loop oscillating frequency ?0 by using a beat note created by the selection of two optical longitudinal modes from the mode-locked laser. The beat note is detected and divided down to drive a modulator that mode-locks the laser. The frequency division stage also reduces the noise.

Abstract: A control method for a laser diode is conducted such that optical output and OMA (optical modulation amplitude) or extinction ratio of the laser diode are controlled while modulating the optical output of the laser diode by applying a bias current and a modulation current to the laser diode. The method has: a first step of measuring the optical output of the laser diode; a second step of measuring a slope efficiency or a corresponding value of the slope efficiency while conducting APC (automatic power control) to adjust the bias current such that the optical output coincides with a predetermined value; and a third step of adjusting the modulation current by AAC (automatic amplitude control) according to the slope efficiency or the corresponding value of the slope efficiency such that the OMA or extinction ratio coincides with a predetermined value.

Abstract: A highly portable, high-powered infrared laser source is produced by intermittent operation of a quantum cascade laser power regulated to a predetermined operating range that permits passive cooling. The regulation process may boost battery voltage allowing the use of more compact, low-voltage batteries.

Abstract: According to one embodiment of the present invention, a programmable light source comprises one or more semiconductor lasers, a wavelength conversion device, and a laser controller. The controller is programmed to operate the semiconductor laser using a modulated feedback control signal. The wavelength control signal is adjusted based on the results of a comparison of a detected intensity signal with a feedback signal to align the lasing wavelength with the conversion efficiency peak of the wavelength conversion device. Laser controllers and projections systems operating according to the control concepts of the present invention are also provided.

Abstract: A method embodiment of the invention includes a scheme for trimming and compensation of a laser emitter in a fiber optic link. A laser emitter is provided. Also a reference optical power value is determined using data models of laser emitter performance generated by statistical analysis of sample population of lasers that are similar to the subject laser emitter. The performance of the subject laser is measured and qualified optical power levels for the subject laser emitter are determined using the reference operating power value and measured performance of the subject laser emitter. The driving current of the subject laser emitter is adjusted to compensate for changes in temperature until the optical power of the subject laser emitter obtains a desired qualified optical power level. Related methods of determining qualified optical power levels for a laser emitter in a fiber optic link are also disclosed.

Abstract: A method for a calibration module to calibrate laser bias current in an optical transceiver. The method comprises causing the calibration module to configure a control module of the optical transceiver for a calibration operation, causing the calibration module to determine a laser bias current monitored by the control module, and determining one or more calibration factor values that cause the laser bias current monitored by the control module to substantially match a laser bias current as measured by an external test meter.

Abstract: An automatic power control system provides a control signal that regulates the output power of at least one laser diode. Coarse adjustment of the control signal is provided by a first means, preferably a digital variable resistor, while fine adjustment and compensation is provided by a second means, preferably by a digital-to-analog converter that receives an input signal proportional to a sensed control system parameter. The control system includes an operational amplifier having a first input coupled to sense output power, and a second input coupled to a DAC to provide finer resolution control. Memory can store system parameter or system parameter variations that can be coupled to the DAC and/or variable resistor to enhance system stability over ambient variations.

Abstract: An optical device, including: a surface emitting semiconductor laser; and a photodetection device for detecting part of laser light emitted from the surface emitting semiconductor laser; the photodetection device including a light absorbing layer and a first contact layer; and the first contact layer being formed with a semiconductor having an absorption edge wavelength smaller than an oscillation wavelength of the surface emitting semiconductor laser.

Abstract: Laser driver systems and methods are provided for controlling a laser driver coupled to a suitable laser source. The laser driver comprises a plurality of current sources, including at least one bias current source and at least two switched current sources. To control the laser driver, a laser power control signal is provided for each switched current source that corresponds to a desired laser output power. An output power error measure is defined based upon an error between a measured laser output power and the desired laser output power for each switched current source and a control system is characterized in which the output power error measures combine to change a magnitude of each of the switched current sources and the bias current source(s) such that the output power error measures converge over time.

Abstract: The invention includes a method for seeding and stabilizing an optical device, including a continuous wave laser, a pulsed laser or a parametric system, having an adjustable cavity length and an output. The illustrated embodiment is a Q-switched Nd:Yag or Brilliant A pulsed laser, but the principles of the invention could be literally applied to other types of lasers, including continuous wave lasers and to any parametric optical device whose operation depends in whole or part on the effective optical length of a cavity. The method comprises the steps of seeding the optical device with a seed signal, generating a feedback signal from the output of the optical device; and adjusting the effective optical length of the cavity of the optical device to maintain stable operation of the optical device by means of the feedback signal.

Abstract: A method for seeding and stabilizing an optical device, wherein the optical device includes one of a continuous wave laser, a pulsed laser, and a parametric system, the method including seeding the optical device with a seed signal, generating a feedback signal from an output of the optical device, and adjusting a wavelength of the seed signal to maintain a stable operation of the optical device based on the feedback signal. An apparatus, including an optical device having a cavity, a seed laser for generating a seed signal coupled to the optical device, a feedback generator coupled to the output of the optical device for generating a feedback signal, and means for adjusting a wavelength of the seed laser to maintain a stable operation of the optical device based on the feedback signal.

Abstract: Threshold current may be determined and one or more bias sources may be programmed in a laser drive circuit. For example, a laser diode emits light along first and second optical paths. A polarizer is positioned in the first optical path between the laser diode and a first detector, which outputs a first detector signal corresponding to the measured optical power of polarized light. A second detector monitors light along the second optical path and provides a second detector signal. A bias compensation circuit receives the first and second detector signals and provides a bias current control signal, which is utilized to program a bias current source supplied to the laser diode. Additionally, multiple polarizer devices may be utilized e.g., a first polarizer in a first optical path aligned with the laser beam and a second polarizer in a second optical path aligned substantially orthogonal to the polarization of the laser beam.

Abstract: Laser modulation is controlled by using a measurement of the average output power level of the laser to adjust the amplitude of the modulation current as necessary to prevent the laser from being over- or under-modulated and to adjust the amplitude of the bias current as necessary to maintain the average output power level of the laser at a desired, reasonably constant level. The laser controller receives an electrical feedback signal from a laser output power monitoring device and uses this signal to obtain the measurement of the average output power level of the laser. Based on this measurement, a bias current control signal and a modulation current control signal are generated and output to the laser driver to cause the laser driver to set the amplitude of the bias current to achieve a desired average output power level and to set the amplitude of the modulation current to prevent over- and under-modulation.

Abstract: A pulse oscillating type solid laser unit that has a laser unit body whose exciting source is a laser diode that emits light in a principal energy absorbing spectrum of a solid laser activated media, and characterized by that prior to radiating laser light outside the laser unit body as a calibrating operation of a pulse laser output value, specified several varieties of rectangle pulse current values are conducted to a laser diode inside the pulse oscillating type solid laser unit so as to pulse-oscillate the laser unit body, a mean laser output value in each rectangle pulse current value is measured by the use of a laser output measuring instrument arranged inside the laser unit body so as to obtain a mean laser output value data, and in case that the laser output light is radiated outside the laser unit body, a pulse current value linear-predicted based on an obtained mean output value data is conducted to the laser diode so as to obtain a desired pulse laser output value.

Abstract: Systems and methods for optically pumping alkali-metal atoms using Coherence Population Trapping (CPT) resonances are disclosed. An illustrative push-pull optical pumping system for inducing CPT resonances in a resonance cell containing an admixture of alkali-metal atoms and one or more buffer gasses may include a laser assembly adapted to produce alternating orthogonally polarized light, and at least one DC current source adapted to output a constant-intensity carrier current signal for inducing laser emission from the laser assembly at a carrier wavelength of the alkali-metal atoms. An RF modulated signal outputted from an RF modulation source can be rectified, split, and phase-shifted for inducing a time-dependent polarization of the laser light that can be used to enhance CPT resonances.

Abstract: An optical amplifier including: a photonic gain clement; and, a transistor electromagnetically coupled to the gain element to inject current into the gain element responsively to the internal optical intensity of the gain element. The coupling of the transistor and the photonic gain element is such that as the optical intensity within the photonic gain element increases, the current injected by the transistor increases, thereby preventing filamentation in the photonic gain element.

Abstract: A semiconductor laser light emitting circuit includes a semiconductor laser diode emitting a laser light by modulating a current supplied thereto, a light intensity detection circuit that detects the laser light and generates a voltage, and a voltage-current conversion circuit converting a voltage into a current supplied to the laser diode. A S/H capacitance is provided to store electric charge and output a voltage to the voltage/current conversion circuit. A first operational amplifier is provided to output a first current charging the S/H capacitance. A rapidly charging circuit is provided to charge the S/H capacitance with a second current. The rapidly charging circuit terminates charging when the voltage is equal to or more than a second reference voltage.

Abstract: Methods and apparatus for managing thermal loads on a laser gain medium and for boosting the output power of a diode pumped laser are disclosed. The short-term average pumping power to the gain medium is increased, to provide a burst of pumping energy to the laser gain medium. A subsequent short-term reduction in the average pumping power then allows the gain medium to cool to a desired state steady level. The average pumping power is then increased to maintain this steady state level until the next burst is desired. For example, a pulse of current may be applied to a laser diode at a first current level I1 for a first time interval ?t1, where I1 exceeds a nominal current value Inom by an amount ?I1. The current to the laser diode is reduced to a second current level I2 for a second time interval ?t2, where Inom exceeds I2 by an amount ?I2. To balance the thermal load on the diode an integral of ?I1 over the time ?t1 is approximately equal in magnitude to an integral of ?I2 over the time ?t2.

Abstract: A system for real-time linewidth reduction in an optical source includes a laser device comprising a back facet, wherein the laser device receives a modulated input current and generates an optical output signal; an etalon device disposed adjacent to the back facet of the laser device, wherein the etalon device receives an optical feedback output signal from the back facet of the laser device, and wherein the etalon device monitors the optical feedback output signal for changes in frequency and, if they exist, generates an optical correction output signal; a photo-detector device disposed adjacent to the etalon device, wherein the photo-detector device receives the optical feedback and correction output signals, and wherein the photo-detector device converts the optical feedback and correction output signals into an electrical signal; and a feedback correction loop coupled to the photo-detector device, wherein the feedback correction loop receives the electrical signal from the photo-detector device and gener

Abstract: A voltage dividing apparatus for preventing sudden increases in power to a laser diode includes a laser diode module, a laser-driving unit and a Zener diode. The laser diode module includes a laser diode for receiving a driving current to emit light, and a photo diode for receiving the light emitted from the laser diode and transferring the light signal into a voltage signal. The voltage signal is fed back to the laser diode module for automatically balancing the power of the laser diode. The laser-driving unit is used for driving the laser diode to output power. When the circuit shorts, two voltage-dividing resistors and the Zener diode disable the laser-driving unit to protect the laser diode. It blocks the laser diode's outputting power to prevent the outputting power from suddenly increasing and prevent the laser with strong power from hurting a user's eyes.

Abstract: A laser scanning device includes a semiconductor laser that emits a laser beam, a laser power detector that detects laser beam power of the semiconductor laser, a reference voltage generator that generates reference voltage for controlling the laser beam power of the semiconductor laser in accordance with a laser power control signal provided from an external device, and a laser driver that compares the reference voltage generated by the reference voltage generator and the laser beam power detected by the laser power detector to control a driving current supplied to the semiconductor laser for emitting the laser beam. The laser scanning device further includes an abnormal condition detector that detects the laser power control signal received by the reference voltage generator.

Abstract: A method includes a scheme for trimming and compensation for a laser emitter in a fiber optic link. Data models of laser performance are provided and used to determine a base power level. It is then confirmed that the base power level is satisfactory. If necessary, adjustments are made to a set of user specified performance parameters until a satisfactory base power level is obtained. Then a table or relation of temperatures and associated current and target average optical power values is generated such that they can be used to regulate laser emitter performance over a range of temperature. Additionally, fiber optic links capable of trimming and compensation are also disclosed.

Abstract: A DBR semiconductor laser is controlled in an image projecting apparatus, which includes the DBR laser having a phase and DBR region, a light wavelength converting device for converting fundamental-wave light emitted from the DBR laser into second harmonic wave light, an optical deflector for scanning the second harmonic wave in a one or two-dimensional manner, and a modulating portion for modulating the DBR laser. Coefficient calculating and wavelength adjusting steps are performed within a non-drawing time. The coefficient calculating step calculates at least one coefficient in a relationship between a DBR current to be injected into the DBR region and a phase current to be injected into the phase region for continuously shifting the wavelength of the fundamental-wave light. The wavelength adjusting step changes DBR current injected into the DBR region and phase current injected into the phase region based on the relationship.

Abstract: A method of and an apparatus for controlling a power of a light emitter in an optical disc drive to stabilize a servo control operation by efficiently compensating a slow tail effect occurring in a photodiode monitoring outputs of the light emitter are provided. The method includes: detecting an intensity of a laser signal reflected from a recording medium; normalizing the reference value using the detected value; and adjusting the reference value using the normalization result.

Abstract: The object of the present invention is to provide an optical module for the WDM communication system, in which the oscillation wavelength is on the grid of the WDM regulation, moreover the optical output power and the oscillation wavelength can be controlled independently. The present module comprises a semiconductor light-emitting device, a wedge shaped etalon device and two light-receiving devices. The etalon device contains a first portion, on which the anti-reflection films are coated, and a second portion. One of the receiving devices detects light transmitted through the first portion of the etalon device, while the other device detects light through the second portion. Signal from the former device controls the output power of the light-emitting device, while the signal from the latter receiving device controls the oscillation wavelength of the laser.

Abstract: An infrared laser has a seed laser with an optical seed output. A pump amplifier receives the optical seed output and has an amplified output. A molecular gas laser receives the amplified output and has an infrared optical output.

Abstract: An arrangement for generating a high power optical radar beam. The arrangement includes first and second laser sources each having a first laser for generating an optical beam of a relatively low frequency F1 and a second laser for generating an optical beam of relatively higher frequency F2. Each laser source provides a first optical beam of frequency F2 and a second optical beam of frequency F1+F2. The arrangement also includes first and second waveform generators each having a modulator and a mixer. A first waveform generator receives the optical beams from the first laser source and a modulation signal for modulating the F1+F2 optical beam. The first waveform generator is operative to provide an output optical beam of frequency F1 having all of the modulation applied to the optical beam of frequency F1+F2.

Abstract: The present invention provides a compact analog directly modulated laser configuration that is suitable for use in the field that uses electrical feedback to compensate for non-linearity in real time, such that no matter how the LI curve changes, the electrical feedback compensates for non-linearity by amplifying a portion of the output analog optical signal and combining it with the input analog electrical signal using the standard control method of negative feedback. When the gain of the feedback loop is relatively high, the overall transfer function of the system is primarily dependent on the feedback loop gain block, which is substantially linear. This is accomplished by incorporating a relatively large bandwidth photo-detector at the back facet of the laser that both monitors the output power of the system and provides a feedback signal to the linearization control circuit, as well as an amplifier.

Abstract: In a light source constructed from a plurality of laser diodes, the overall light output of the light source is controlled based on calibration data which is generated for each pair consisting of any one of the plurality of laser diodes and a dedicated control board for controlling the light output of the one laser diode, and which defines a correspondence between the control value for driving the control board and the value of the light output of the laser diode measured when the control board is driven based on the control value, and when replacing a designated one of the laser diodes in the light source, the designated laser diode and its dedicated control board are replaced together with the corresponding calibration data.

Abstract: The invention relates to an optical output system with auto optical power control for an optical mouse. The optical output system comprises: a light emitting device, a driver and an auto power controller. The light emitting device is used for generating emitting light. The driver is used for driving the light emitting device. The auto power controller is used for outputting a control signal to the driver according to at least one input signals so as to control the power of the light emitting device at a predetermined range. According to the invention, the optical output system can output the stable power of the emitting light at a predetermined value within the predetermined range under various conduction and circumference by a feedback control. Furthermore, the optical mouse using the optical output system can work on various reflective surface.

Abstract: A system, apparatus, and method may provide laser beams of two or more wavelengths from diode pumped solid-state laser sources (220, 222, 224). The beam paths of these laser beams with different wavelengths, which are generated by the laser sources (220, 222, 224), may be aligned along a common optical axis 280 by an optical configuration, to treat at least one target area. Frequency-doubled laser beams, output from a plurality of diode pumped solid state laser cavities, may be passed through fold mirrors (M2, M5, M8), and combined on a common optical axis 280, using one or more combiner mirrors (M10, M11, M12), to unify the beam paths. Selected laser beams may be delivered to a target using one or more delivery systems.

Abstract: This laser processing apparatus includes an amp fiber, a seed laser oscillating unit, a fiber core exciting unit, a laser emitting unit, a controlling unit, a light sensor, etc. A Q-switched pulse seed laser beam from the seed oscillating unit enters into one end surface of the amp fiber, and a continuously oscillated core excitation light from the fiber core exciting unit 14 enters into the other end surface. The seed laser beam is amplified in the activated core during the propagation through the amp fiber and comes out as a high-power processing laser beam from the other end surface of the amp fiber. The light sensor 64 feeds back the laser power of the processing laser beam to the seed laser oscillating unit.

Abstract: A method and apparatus are provided to modulate a beam of laser light. An acousto-optic modulator (AOM) is positioned to receive continuous-wave (CW) laser light at an angle approximating the Bragg angle. Fine tuning of the modulation is then used to compensate for any variations in the actual angle from the Bragg angle. A photodiode provides a feedback signal that may be used to tune or adjust the operation of the AOM. The photodiode is positioned to receive laser light at the first order diffraction and provide a signal indicative of the magnitude of the first order diffraction laser light produced by the AOM. The photodiode signal is coupled to an RF frequency generator so that the RF frequency may be adjusted to vary the acoustic wave in the AOM to compensate for any variations in the Bragg angle.

Abstract: A single-frequency Brillouin fiber ring laser with extremely narrow linewidth comprises a single-frequency narrow-linewidth rapid-tunable pump laser, a temperature-controlled acoustically-damped package for Brillouin fiber ring laser cavity, and an auto-tracking feedback electronic loop with novel configuration for active stabilization. The Pound-Drever-Hall frequency-locking technique is employed to keep pump laser frequency in resonance with one of the Brillouin fiber ring cavity modes. Instead of changing cavity length of Brillouin fiber ring laser, the pump laser frequency is rapidly tuned in the auto-tracking feedback electronic loop. This enables extremely narrow linewidth radiation emitted from a Brillouin fiber ring laser without stretching the fiber ring.